In a related art of an inverter air conditioner, a refrigerant pressure and a load are heavier when the inverter air conditioner runs at a high frequency. If a compressor of the inverter air conditioner is stopped directly at the high frequency, energy of the refrigerant pressure and of the load may be released instantly such that a vibration and stress of a piping is too large and even there is a danger to break the piping. In the related art, it is generally to reduce the frequency to control the compressor to stop. That is, the frequency of the compressor is reduced to a low frequency and then the compressor is stopped. As a result, the vibration and stress of the piping is reduced at a moment that the compressor is stopped. However, the vibration and stress of the piping is still high at the moment that the compressor of the inverter air conditioner is stopped.